Method of treating coal and product thereof



' Patented Feb. 25, 1930 UNITED STATES PATENT o FIca anon: runny AND NATHANIEL Io Drawing.

This invention relates to the treatment of storage anthracite coal to remove therefrom the surface discoloration which takes place in storage and to restore essentially the original appearance of the fresh mined coal.

Iresh mined coal, that is coal which is mined and shippe dfor immediate consumption has a jetblack color and a bright luster. Owing to the seasonal demand for coal, large quantities of fresh mined coal are placed in storage-whenever possible in order to avert a shortage in the fall and winter months. Such coal is known in the trade as storage coal. Coal so stored does not deteriorate as a fuel but the physical appearance is altered. The

coal becomes a dull grey in appearance and a considerable portion of it becomes badly discolored by metallic compounds. The consuming public," who are accustomed to recognize anthracite coalby its jet black color and luster often assume that coal which has been held in storage and has thus lost is characteristic appearance is poor in quality. The original fresh mined coal appearance can- 'not be restored by ordinary washing. Consequently serious losses are sustained by the producer because this storage coal does not command the price of fresh mined coal, although analysis indicates that the change 30 is only one of appearance and there is no loss of fuel value or consequential change in chemical composition.

It is the object of the present invention to provide a method of treating storage coal to remove the surface discoloration and restore its original charactertistic color and bright luster;

The iron in the mineral matter of coal is considered to be almost wholly present in combination with sulphur. Under the influence of atmospheric exposure the iron sulhides become oxidized presumably to insolule basic sulphates, ox1des, and other compounds imparting to the coal a rusty appearance. Other reactions go on and other metallic compounds may show on the surface, The longer the coal is in storage and consequently the longer it is exposed to atmospheric nfluences the reater usually becomes the discoloration. 0 far as we are aware, these disacid, formic acid, hydrochloric acid, acid R. LANDON, OF MQUN'I KISCO, NEW YORK, ASSIGN- ORS TO DELAWARE, LACKAWANNA & WESTERN N. Y., .A. CORPORATION OFJVEW JERSEY.

COAL COMPANY, 01E NEW YORK,

mmnon on. TREATING coax. AND Eeaonuc'r 'rnnanon Application filed February 25, 1929, Serial No. 342,800.

colorations have never been removed in a practtical way by any previous known'treatmen We have discovered that the surface discoloration of storage coal can be removed and the original appearance of the coal restored by treating the coal under appropriate conditions with acidsor with acid salts. Numerous acids and acid salts, of which oxalic fluoride of soda and sodium acid fluo-sulfate are examples, can be used and the selection will depend on questions of economy and the nature and degree of the discoloration. We, therefore, do not limit ourselves to any par ticular acid or acid salt or to single acids, as mixed acids and acid salts can be used. F or the treatment of badly discolored coal, among the acids, oxalic acid is particularly eflicient, and of the acid salts, sodium acid fluosulphate is effective.

. As an example of the method, we may proceed as follows,ten parts of oxalic acid crystals are dissolved in one hundred parts of water and the discolored coal is immersed in this solution at normal temperatures for a period-sufficient to accomplish the object,

. usually a few minutes, after which the coal is removed from the solution and may be washed or sprayed with water.

The action is more rapid and thorough if the coal is agitated in the solution, thereby producing ascrubbing action. A practical means ofaccomplishing this action 1s by use of a jig, well known in the coal industry as an apparatus of separating coal from impurities, the principle of which is based on the difference in specific gravity of coal and rock or slate. This separation in the preparation of domestic sizes of anthracite is accomplished in a large tank filled with water. The action of a. plunger about two feet below the surface floats the coal to the surface, whence it can be removed. Instead of water, the jig is filled with acid-solution when it is desired to treat coal for the purpose of removing the discoloration.

While we have described the use of a 10% solution of oxalic acid at normal temperature, by treating the coal at higher temperatreat the coal with it at temperatures above 6 normal.

The acid solution can be recovered and be reused until it becomes too heavily contaminated with substances dissolved from the coal, the degree of acidity being maintained by .the periodic addition of small quantities of acid or acid salt.

As indicated herein, this invention is not restricted to the application to the coal of any particular acid solution, the essence of this invention residing particularly in the restoration of the original color. and luster of the coal. Various changes may be made, therefore, in the procedure and the chemicals employed hereinwithout departing from the invention or'sacrificing any of the advantages thereof.

We claim:

1. Anthracite coal that has become discolored treated with an acid to remove there'- i'rom the discoloration.

2. Anthracite coal that has become discolored treated with oxalic acid to remove therefrom the discoloration.

3. The method of restoring-the luster and improving the appearance of coal which comprises treating the coal with .an acid capable of removing the discoloration therefrom. 4. The method of restoring the luster and improving the appearance of coal which comprises treating the coal with an acidic solution capable of removing the discoloration therefrom.

5. The method of restorin the luster and improving the appearance 0 discolored coal which comprises treating it with oxalic acid.

In testimony whereof we aflix our signatures.

, ELIOT FARLEY.

NATHANIEL R. LANDON.

DISCLAIMER 1,748,335. Eli0t Farley and Nathaniel R. Landon, Mount Kisco, N. Y. METHOD. Patent dated February 25, 1930. Disclaimer filed March .3, 1936, by the assignee, Delaware Lacka- OF TREATING COAL AND PRODUCT THEREOF.

, wanna ct: Western Coal Company. Hereby disclaims: (a) Claims 1 and 2 of said Letters Patent. (b) Froin claims 3 and 4 of said Letters Patent any and all methods of restormg the luster and mproving the appearance of coal by treating the coal with an acid or acidic solution in which the acid or acidic solution does not consist of oxalic acid, formic acid, hydrochloric acid, acid fluoride of soda, or sodium acid fluosulphate or mixtures thereof.

[Qflimal Gazette March 24, 1936.] 

